1. Field of the Invention
The invention relates to a noise reduction device and method, and particularly to a noise reduction device and method for reducing noises of a video sequence.
2. Description of the Prior Art
How to reduce noises of an image frame is a main issue of the flat display technique. When an image frame has noises, users will not be satisfied with the quality of the image frame. Generally, common video inferences (VIF) include interpreting signals, ripples of a video, and blocking effect of JPG/MPEG decompression.
Methods for reducing noises of an image frame include a 2D noise reduction (2DNR) method and a 3D noise reduction (3DNR) method. Generally, the 2DNR method utilizes multiple adjacent pixels in the present image frame to adjust the present image frame. The 3DNR method utilizes multiple continuous image frames to adjust the present image frame. The 2DNR method has an obvious disadvantage, which leads the detail of an image to become blurry. Although the 3DNR method does not have the disadvantage of the 2DNR method, the 3DNR method has disadvantages of ghosts and greater hardware resource requirement.
Please refer to FIG. 1A and FIG. 1B. FIG. 1A is a schematic diagram illustrating five continuous image frames of a video sequence. FIG. 1B is a schematic diagram illustrating an image frame superposed by the five image frames shown in FIG. 1A. As shown in FIG. 1A, according to the five continuous image frames, an object in these image frames is moving. Traditional 3DNR method utilizes a superposition of multiple image frames to reduce noises, so the ghosts is generated obviously shown in FIG. 1B after superposing multiple continuous image frames shown in FIG. 1A. The ghosts are generated easily if the image frames change rapidly, for example, fast movement, dissolving, disappearing, and so on. Additionally, the 3DNR method utilizes multiple continuous image frames to adjust the present image frame, so it takes more hardware resource. Therefore, neither the 3DNR and 2DNR methods can effectively reduce the noises without respect to a static or a dynamic image frame.
Therefore, the invention provides a noise reduction device and a method for reducing noises of a video sequence, further solving the aforesaid problems.